When I first read your thread title before popping in here I would have either said that your speakers were too close to the rear wall or you're sitting to far from them.
But after reading your post I think it has more to do with the amp and/or its synergy with your speakers and preamp. Does the Rogue have an ultra low input impedance? A bad set of tubes? Or maybe as Nsgarch suggests, that you try switching modes on the Magnum 120s or using different taps.
But after reading your post I think it has more to do with the amp and/or its synergy with your speakers and preamp. Does the Rogue have an ultra low input impedance? A bad set of tubes? Or maybe as Nsgarch suggests, that you try switching modes on the Magnum 120s or using different taps.